1. Field of the Invention
The present invention generally relates to the field of semantic descriptions for content data. More particularly, the present invention relates to the field of methods and systems for implementing powerful and flexible semantic description tools to describe the underlying meaning of the content data.
2. Related Art
The MPEG-7 “Multimedia Content Description Interface” standard which is being developed by the Moving Pictures Expert Group (MPEG) focuses, unlike the preceding MPEG standards (e.g., MPEG-1, MPEG-2, and MPEG-4), on representing information about the content data, not the content data itself. The goal of the MPEG-7 standard is to provide a rich set of standardized tools to describe content data. In particular, MPEG-7 seeks to provide a simple, flexible, interoperable solution to the problems of indexing, searching, and retrieving content data. More specifically, MPEG-7 aims to standardize a core set of Descriptors that can be used to describe the various features of the content data; pre-defined structures of Descriptors and their relationships, called Description Schemes; a language to define Description Schemes and Descriptors, called the Description Definition Language (DDL); and coded representations of descriptions to enable efficient storage and fast access. The DDL is being based on XML Schema. Moreover, the MPEG-7 descriptions (a set of instantiated Description Schemes) are linked to the content data itself to allow fast and efficient searching for material of a user's interest.
Continuing, MPEG-7 intends to describe content data regardless of storage, coding, display, transmission, medium, or technology. MPEG-7 addresses a wide variety of media types including: still pictures, graphics, 3D models, audio, speech, video, and any combination thereof (e.g., multimedia presentations, scenarios, etc.). Examples of content data within the MPEG-7 standard include an MPEG-4 data stream; a video tape; a CD containing music, sound, or speech; a picture printed on paper, and an interactive multimedia installation on the Web (i.e., the Internet).
The MPEG-7 standard includes different types of Descriptors and Description Schemes. Some Descriptors and Description Schemes describe what is in the content data in terms of syntactic structure, color histogram, shape of an object, texture, motion, pitch, rhythm, etc.
On the other hand, semantic Description Schemes describe the underlying meaning or understanding of the content data. In particular, a goal, advertisement, and Madonna are examples of a semantic description (an instantiated semantic Description Scheme). Other examples of semantic descriptions includes a storyline for a movie (i.e., content data), a description of a scene in the movie, a description of an image, a description of a piece of music, etc.
Again, the semantic description is based on the underlying meaning of the content data. Typically, the semantic description is expressed with words. Unfortunately, computer systems or other computational systems are not able to usefully manipulate (e.g., create, exchange, retrieve, etc.) semantic descriptions expressed with only words. However, if structure is incorporated into the semantic descriptions, a computer system or other computational system can usefully manipulate semantic descriptions having structure. For example, it is not sufficient to describe the movie Zorro as having the entities Zorro, Zorro's girlfriend, a bad guy, a first sword fight, a second sword fight, etc. Relationships between these entities are needed, hence providing the structure.
Numerous proposals have been made to limit the types of structure to be incorporated into the semantic descriptions of the MPEG-7 standard. In particular, these proposals advocate creating specific, static semantic description schemes having only certain types of structure. Moreover, these proposals further encourage setting-up and running experiments to verify these specific, static semantic description schemes.
There are several problems with these proposals. First, these experiments can conclude that these specific, static semantic description schemes function well during these experiments because of the conditions of the experiments. Yet, these specific, static semantic description schemes can still fail when applied to new descriptive situations. For example, if these specific, static semantic description schemes can be applied to describe a soccer game, there is no way of knowing whether these specific, static semantic description schemes can be applied to describe a human birth. Secondly, these experiments do not indicate or help to determine the range of semantic descriptions that are impossible to implement or no longer capable of being implemented with these specific, static semantic description schemes because of the limitation on the types of structure incorporated.